And yet the reason you believe Barr is equally applicable to the testimony of Hillary or pretty much anyone testifying before Congress.
"'Spinning' there would likely put himself in jeopardy, why would he do that?"
People, including, perhaps, Hillary, "spin" before Congress. They put things in a particular way to give impressions, given that such spin does not entail a provable lie under oath. "I think spying occurred," is a good example. There is literally no reason that Barr would fear consequences of saying this, since there are no consequences. Unless there are memos written by Barr saying that he does not believe spying occurred, no one could prove that this is a lie whether or not it is.
What jeopardy do you see for Barr saying that he thinks spying occurred when he does not? The term "spying" is itself vague. If surveillance counts as spying, then surely he's right. There was some surveillance of Trump campaign members, if I'm not mistaken. But "spying" makes it sound rather sinister, just as his boss would like it.